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Spitzer Mid-Infrared Spectroscopy of Infrared Luminous Galaxies at z~2 I: the Spectra

Lin Yan·Anna Sajina·Dario Fadda·Phil Choi·Lee Armus·George Helou·Harry Teplitz·David Frayer·Jason Surace
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Abstract

We present the mid-infrared (MIR) spectra obtained with the Spitzer InfraRed Spectrograph (IRS) for a sample of 52 sources, selected as infrared luminous, z>1 candidates in the Extragalactic First Look Survey (XFLS). The sample selection criteria are f(24um) > 0.9mJy, nu fnu(24um)/nu fnu(8um) > 3.16 and nu fnu(24um)/nu fnu(0.7um) > 10. Of the 52 spectra, 47 (90%) produced measurable redshifts based solely on the mid-IR spectral features, with the majority (35/47=74%) at 1.5 1. Their $L_{1600Å}$ and $L_{\rm IR}$ suggest that our sample is among the most luminous and most dust enshrouded systems of its epoch . Our study has revealed a significant population of dust enshrouded galaxies at z~2, whose enormous energy output, comparable to that of quasars, is generated by AGN as well as starburst. This IR luminous population has very little overlap with sub-mm and UV-selected populations (Abridged).

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Lin Yan, Anna Sajina, Dario Fadda, Phil Choi, Lee Armus, George Helou, Harry Teplitz, David Frayer, Jason Surace. 2006-12-12. Spitzer Mid-Infrared Spectroscopy of Infrared Luminous Galaxies at z~2 I: the Spectra. https://doi.org/10.1086/511516

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